1. Field of the Invention
This invention relates to a vehicle suspension damper which is remotely controlled.
2. Description of the Prior Art
Vehicle suspension dampers have taken a myriad of forms in the past fifty years. Many types of valving have been proposed as solutions to the long perceived need for better ride control. Although most vehicle suspension dampers stand alone and thus have no external control, remotely controlled devices have been proposed. U.S. Pat. No. 2,698,068, for example, discloses a vehicle "dive arrester" which uses hydraulic brake pressure to lock up a shock absorber whenever the vehicle's service brakes are applied. The brake system pressure acts upon a small piston housed within the shock absorber's main piston to cut off flow through the main piston by displacing the smaller piston. This system is incapable, however, of providing a variable response independent of brake line pressure. Also, no response is possible when the brakes are not actuated.
U.S. Pat. No. 3,146,862 discloses a hydraulic shock absorber having an external piston and cylinder remotely actuatable by hydraulic pressure and coupled by means of a push rod to a spool valve located within the piston rod. The spool valve limits flow through a passageway formed within the piston rod. Because of the weight of the pushrod, piston, and valve, this system is not capable of very low response times.
Other examples of remotely controlled shock absorbers are shown in U.S. Pat. No. 3,532,194 which discloses a vacuum operable variable damping system incorporating an adjustable base valve and U.S. Pat. No. 3,827,538 which discloses a remotely controlled shock absorber having a gear driven valve system including a central control rod running through the piston rod and orifice-containing disk plates adjustable to alter the shock absorber damping characteristics. Finally, U.S. Pat. No. 4,463,839 discloses a shock absorber having a two-position valve operated by a similar central control rod driven by a solenoid motor. These systems could all be expected to suffer from response time problems because, for example, the vacuum operated system would lack the necessary power for fast response, and the gear and solenoid driver system would have hindering inertia resulting from the weight of the moving parts. Additionally, the solenoid-driven system lacks flexibility because the solenoid can be positioned only in discrete locations.
It is an object of the present invention to provide a vehicle suspension damper having variable remotely controllable damping capability.
It is another object of the present invention, then, to provide a damper characterized by low response time.